probably related to this post, about diy expanders, and potential for creating your own.
there is a ‘control port’ on the back of the MM, which Id guess is i2c + power.
(Id assume the audio expander is i2s?)
we don’t have pin outs for the expansion points, nor tech details.
what voltage level are used 3v3 or 5v on i2c? master ? pull down?
this is really important, often these expansion ports have NO protection, so easy to blow up your module.
bare in mind, i2c was never designed to be a user-level connection, frankly its adoption in eurorack was a pretty questionable move.
anyway, if 4ms do allow for custom expanders by ‘users’, for diy purposes, they will publish the above.
more generally, as this would also be relevant to an i2c expander…
i2c is just the wire protocol, it does not infer how its used, basically its just a bunch of registers.
this is ok, for things like switches/faders which just have a simple value, that can be almost a ‘generic’ use-case.
however, but more complex use cases require a protocol on top, which would have to be supported by the ‘host’ (e.g. MM)
not sure how 4ms plan to handle this on the MM.
my assumption, is the core firmware wouldn’t do much with it, rather it would just allow ‘user modules’ access to read/write i2c registers (in an abstract way).
this would allow 3rd parties to implement modules for specific use-cases e.g. other eurorack modules.
(we cannot expect 4ms to code for every i2c capable eurorack module)
also… I wonder if it will only handle i2c slave modules?
this would rule out things likes Teletype which are masters.
or will it support i2c multi master, as some chipsets do?
though, Im not sure if this only works if all other masters are also multi master.
Ive been looking at this with another SoC, which has multi master, but to be honest, I decided just supporting slaves was priority, and wont bother with multi master till much later if ever 